Thyroid gland
Cytology / fine needle aspiration

Topic Completed: 1 March 2009

Revised: 7 May 2019

Copyright: 2003-2018,, Inc.

PubMed Search: fine needle aspiration cytology thyroid

See also: cytology section of specific diagnoses
Page views in 2018: 1,397
Page views in 2019 to date: 721
Cite this page: Islam S. Cytology / fine needle aspiration. website. Accessed May 23rd, 2019.
Definition / general
  • FNA is initial step in management of thyroid nodules, to distinguish benign from neoplastic and to diagnose papillary carcinoma (Cancer 2007;111:306)
  • FNA should be considered a screening test, not a diagnostic test
  • Main contraindication is bleeding diathesis, as formation of large hematoma at biopsy site may compress trachea
  • Sensitivity and specificity of FNA are > 90% if specimen adequate, although high false-negative rate exists for detecting thyroid malignancy in males (Am J Surg 2008;195:396)
  • Scrapes have equal value to frozen sections in intraoperative management
  • ThinPrep may be superior to pap stain for epithelial lesions (Cytojournal 2008;5:3)
  • Ultrafast Pap staining detects Orphan Annie eyed clear nuclei of papillary thyroid carcinoma
Diagrams / tables

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Short rapid strokes
with only slight
changes in direction

  • Cannot differentiate follicular or Hürthle cell adenomas from carcinoma, which requires surgical excision to detect capsular or vascular invasion
  • Cannot diagnose follicular variant of papillary carcinoma, although cases with features suspicious for papillary carcinoma have higher malignancy rate (72%) than those diagnosed as follicular neoplasm (22%, Cytojournal 2006;3:9)
Adequate specimens
  • 5 groups of 10 cells each of well preserved follicular epithelium on each of 2 slides
Inadequate specimens
False positives
  • 10%
  • Diagnosis of malignancy often based on only 1 or 2 atypical cytologic features
False negatives
  • 25%
  • Marginally adequate specimens; for papillary thyroid carcinoma, may be due to nodule heterogeneity (Cancer 2008;114:27)
Lymph nodes
  • Measurement of thyroglobulin in FNA from lymph nodes in patients with history of papillary thyroid carcinoma is useful in detecting recurrent disease, especially if specimen is or likely will be inadequate for evaluation (Cytojournal 2008;5:1)
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